1. Field of the Invention
The present invention relates to a measuring machine. More specifically this invention relates to a measuring machine comprising a base, a guide rail provided on the base with a guide surface thereon, and a movable body slidably provided via an air bearing device on the guide surface of the guide rail.
2. Description of Related Art
Surface texture measuring machines for measuring surface texture such as dimension and profile of the object to be measured have been known. As a representative example of such a surface-texture measuring machine, the known one is three-dimensional measuring machine (refer to, for instance, Japanese Patent Laid-Open Publication No. 2000-65571). Of the three-dimensional measuring machines as described above, there is one in which a gauge head thereof moves in one horizontal direction (X-axial direction) and in direction of gravitational force vertical to the X-axial direction (Z-axial direction), and further a table with an object to be measured placed thereon moves along a guide rail provided on the base in the Y-axial direction perpendicular to the X-axial direction and to the Z-axial direction to measure three-dimensional data of the object to be measured.
In the three-dimensional measuring machine as described above, cast metal is used for the base and table to minimize changes due to aging. For the guide rail, stainless steel is used to prevent rust. As shown in FIG. 4, for instance, a guide rail 92 made of stainless steel is provided on a base 91 for rust prevention.
In the three-dimensional measuring machine based on the conventional technology as described above, it is necessary to assemble the guide rails each manufactured as a discrete component on the base by tightening with screws, which disadvantageously requires a number of steps in the manufacturing process and high cost.
In addition, because of difference in materials for the base 91 and for the guide rail 92, the bimetal effect occurs due to the fine difference of the linear expansion coefficients between the two types of materials, which disadvantageously causes performance degradation such as deviation in measurement.